"I heard rumors of a new zero-day being found and sold after the support period expired [for Windows 2000]," said HD Moore, creator of the popular Metasploit penetration testing toolkit and the chief security officer of security company Rapid7. "But there were few if any examples that ended up in the public eye."
Moore agreed with Fossen that XP bugs would be more valuable after April 2014, but contended that all Windows vulnerabilities would jump in value.
"Something more common [three years ago] was backporting new security advisories into functional exploits on Windows 2000," said Moore in an email. "Every time a server-side vulnerability was found in Windows XP or 2003 Server, quite a few folks looked at whether this would also work against Windows 2000. My guess is that the retirement of Windows XP will result in all Windows vulnerabilities being of slightly higher value, especially given the difference in exploit mitigations between XP and newer platforms."
It's far easier to exploit flaws in Windows XP than in newer editions, such as Windows 7 and Windows 8, noted Moore, because of the additional security measures that Microsoft's baked into the newer operating systems.
Microsoft has said the same. In the second half of 2012, XP's infection rate was 11.3 machines per 1,000 scanned by the company's security software, more than double the 4.5 per 1,000 for Windows 7 SP1 32-bit and triple the 3.3 per 1,000 for Windows 7 SP1 64-bit.
"Windows XP vulnerabilities will be valuable as long as enterprises utilize that version of the operating system," said Brian Gorenc, manager of HP Security Research's Zero Day Initiative, the preeminent bug bounty program. But Gorenc also argued that any XP zero-days would be outweighed by higher-priority hacker work.
"Researchers are primarily focused on the critical applications being deployed on top of the operating system," said Gorenc in an email reply to questions today. "Attackers and exploit kit authors seem to rely on the fact that the update process and tempo for applications are not as well defined as those for operating systems."
Fossen, convinced that XP would be a big fat target after April 8, wondered whether Microsoft might find itself in a tough spot, and back away from the line in the sand it's drawn for XP's retirement.
"If hackers sit on zero-days, then after April use several of them in a short time, that could create a pain threshold [so severe] that people organize and demand patches," said Fossen.
The consensus among analysts and security experts is that Microsoft will not back down from its decision to retire XP, come hell or high water, because it would not only set an unwelcome precedent but also remove any leverage the company and its partners have in convincing laggards to upgrade to a newer edition of Windows.
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